2 Pcs 6 Inch Draft Blocker Backdraft Damper Duct Draft Stopper One-Way Airflow Ducting Insert

Stops outside air from coming into the dryer. Easy to install, ensure you get the airflow direction correct.

Pretty good. It stopped the bad backdraft I had, but the center hinge has a bit more gap than I'd like.

I used two of these with my 4x4x4 foot generator enclosure to keep my 9kw inverter generator cool when running during power outages.

I had a high volume of backdraft coming out of my over the range microwave making the kitchen 12 degrees colder than the rest of the house when it gets cold. I played with the baffle that came with the microwave, which involves taking down the microwave each time, bouncing between allowing it to work but really not stopping any backdraft to it getting stuck preventing any stove venting getting through. If I had bought this 17 dollar (6in black) item before this last cold spell I would have saved hundreds of dollars on heating. Everything is quality with this. For such thin (lighter is better) sheet metal the vanes are perfectly flat and square making full contact with the generous gasket keeping all air out of the house. The lowest setting on the vent fully opens the vanes. Even the paint job, where only a 1/4" section can be seen when installed, looks high quality. Easy to install just pop off the vent cap outside, drop this in to the vent pipe (I then duct taped it because I didn't by a clamp) then tighten the vent cap back on to the other half of this.

These work great for what I need them for. They open and close a few times a day and have been working that way for about seven months now. Simple to install not much else to say.